JSFiddle - React, Tailwind, and code Playground

JavaScript

const calcFunction = function(num) {
  return num * 2;
}

console.log('従来の関数');
console.log('calcFunction 引数2:', calcFunction(2) );
console.log('calcFunction 引数3:', calcFunction(3) );

console.log('----------------------');
console.log('アロー関数');

const calcArrow1 =(num) => {
  return num * 2;
}

console.log('calcArrow1 引数2:', calcArrow1(2) );
console.log('calcArrow1 引数3:', calcArrow1(3) );


console.log('----------------------');
console.log('引数のカッコ省略');

const calcArrow2 =num => {
  return num * 2;
}

console.log('calcArrow2 引数2:', calcArrow2(2) );
console.log('calcArrow2 引数3:', calcArrow2(3) );


console.log('----------------------');
console.log('波カッコ,return 省略');

const calcArrow3 =num => num * 2;

console.log('calcArrow3 引数2:', calcArrow3(2) );
console.log('calcArrow3 引数3:', calcArrow3(3) );


console.log('----------------------');
console.log('戻り値がオブジェクト1');

const calcArrow4 = num => {
  return {
    plus: num + 1,
    double: num * 2
  }
}

console.log('calcArrow4 引数2:', calcArrow4(2) );

console.log('----------------------');
console.log('戻り値がオブジェクト2');

const calcArrow5 = num => ({ plus: num + 1, double: num * 2 })

console.log('calcArrow5 引数2:', calcArrow5(2) );